In the second half of the 20th century, fox rabies became unusually widespread in many European countries due to the adaptation of the rabies virus to a new natural host. Starting at the Polish-Russian border in 1939, a wave of fox rabies epizootic moved to the West at a rate of 30-60 km/year; state borders were not a barrier (Steck & Wandeler, 1980;Winkler, 1975). At the same time, fox rabies began to spread eastward in the former Soviet Union (Deviatkin et al., 2017;Winkler, 1975). In central and western Europe, this problem was managed through the implementation of expensive oral vaccination programs. As a result,

Ixodid ticks (n=3714) from natural foci of Baikal Region (Irkutsk Region and Republic of Buryatia) have been examined for pathogenic Borrelia DNA during 2013-2010. On average 40.9 % of the samples were positive for Borrelia markers during the survey period; the range of variantion was – 32–55 %. The increasing of infection rate in ticks is traced in multi-year trends. During the ticks’ activity season, maximal infection rates have been noted at the end of the season (60 %), minimal – at the very beginning of the season (28,6 %) and on the peak of vectors’ abundance (36-39 %). The significant geographical, species and age differences have been detected in Borrelia infection rate of Ixodid ticks. Borrelia DNA have been detected considerably more often in taiga tick (the main vector of Ixodid tick borrelioses in Siberia) and in its nymphs more often, than in adult ticks. There was no difference in the infection rate of male and female ticks, and also between ticks, collected from the vegetation and from human and animals. The ratio og genotyped Borrelia species had been as follows: 64.2 % – B. garinii, 21,7 % – B. afzelii, 14,2 % – B. miyamotoi. Key words: Ixodid ticks, pathogenic Borrelia, PCR, genotyping, Baikal Region.

No abstract

No abstract

Introduction. Ixodid ticks simultaneously are hosts and vectors of tick-borne encephalitis virus (TBEV), presenting a high risk to humans. Monitoring of the vectors part of TBEV population is usually held by means of express analysis methods (ELISA and PCR), but only isolation and identification of infectious virus is reliable evidence of TBEV circulation in the natural foci. Objectives — to demonstrate the TBEV infection rates of Ixodid ticks from natural TBE foci of Baikal Region, based on comprehensive study, including ELISA, PCR and isolation of virus on laboratory mice (LM) model. Methods. Questing adult Ixodid ticks (n = 20 111, mainly — Ixodes persulcatus Schulze, 1930), were collected in TBE natural foci of Baikal Region during 2013–2020. The suspension on saline solution was prepared from the each tick and analyzed by ELISA first. The samples with positive ELISA results were verified in PCR-RT. Furthermore, randomly selected samples with negative ELISA results were analyzed by PCR. Suspensions with positive ELISA and PCR results have been inoculated to suckling LM intracerebrally. Results. The samples with positive PCR results have been divided into two groups: group 1 — all suspensions with positive ELISA results, group 2 — randomly selected samples with negative ELISA results. The positive PCR results in group 1 made up 70.5 % with average Ct rate 24.9. The positive PCR results in group 2 have been obtained in 2.2 % of cases with average Ct rate 30.7. The isolation on LM model was more successful in group 1 (25.8 vs 13.0 %; р < 0.01; df = 69). Conclusion. ELISA is more useful for study of large amounts of ticks during monitoring of natural TBE foci, offering insight into the epidemically important vectors rate. To get the more full assessment of the ticks’ infection rate one must use ELISA and PCR simultaneously, and sum the results into general rate. For high strains isolation results the LM should be inoculated with the suspensions, which had shown positive both ELISA and PCR results.